Abstract:
BACKGROUND Knowledge of the chemical composition of whole-rock geological samples is the basic work of geochemical research. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has become the most powerful tools of elemental analysis as its advantages of direct solid sampling, avoiding the cumbersome wet chemical digestion process of traditional analytical techniques, low-pollution and low-consumption and high-efficiency. However, the small sample volume of laser ablation cannot represent the chemical composition of complex and inhomogeneous samples, resulting in poor analytical precision and accuracy, which hinders its application in whole-rock bulk analysis. It is critical to prepare complex whole-rock geological samples into homogeneous and stable sample targets.
OBJECTIVES To establish a green and efficient pretreatment technique for LA-ICP-MS whole rock analysis of complex geological samples.
METHODS The samples were first calcined at 1000-1100℃ to remove volatiles, pressed into pellets, and then melted by high-energy wide pulse width infrared laser irradiation to finally obtain a homogeneous and stable sample glass.
RESULTS Compared with pressed powder pellets, the new sample preparation procurement improved the analytical precision of each element in marine sediments GBW07354 and GBW07356 by an average of 7.7 times and 3.9 times, respectively. The deviation between the measured values and reference values of most elements in marine sediment samples was within 10%; the deviation between the measured values and reference values of most major elements, REEs, and other trace elements in soil composition standards was within 5%, 20%, and 15%, respectively; the number of elements measured in bauxite samples reached 40, and the compositions of Sc and W elements were given for the first time.
CONCLUSIONS Rapid and accurate analysis of major and trace elements in marine sediment, soil, and bauxite standard samples has been determined through the optimized pretreatment technique. The sample preparation procurement established in this paper allows the LA-ICP-MS technique to be directly and better applied to the elemental analysis of complex geological whole rock samples, further improving the efficiency of major and trace element analysis in geological samples.
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